Remove old zobrist trick for castling rights

[stockfish] / src / position.cpp

diff --git a/src/position.cpp b/src/position.cpp
index 471ef01f24f16bdbd5581ec170b7c0b062840812..6ef7aedc23f5c3aaa51402e127f07a4dac0b2a60 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -119,15 +119,7 @@ void Position::init() {
       Zobrist::enpassant[f] = rng.rand<Key>();
 
   for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr)
-  {
-      Zobrist::castling[cr] = 0;
-      Bitboard b = cr;
-      while (b)
-      {
-          Key k = Zobrist::castling[1ULL << pop_lsb(&b)];
-          Zobrist::castling[cr] ^= k ? k : rng.rand<Key>();
-      }
-  }
+      Zobrist::castling[cr] = rng.rand<Key>();
 
   Zobrist::side = rng.rand<Key>();
   Zobrist::noPawns = rng.rand<Key>();
@@ -780,9 +772,9 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
   // Update castling rights if needed
   if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to]))
   {
-      int cr = castlingRightsMask[from] | castlingRightsMask[to];
-      k ^= Zobrist::castling[st->castlingRights & cr];
-      st->castlingRights &= ~cr;
+      k ^= Zobrist::castling[st->castlingRights];
+      st->castlingRights &= ~(castlingRightsMask[from] | castlingRightsMask[to]);
+      k ^= Zobrist::castling[st->castlingRights];
   }
 
   // Move the piece. The tricky Chess960 castling is handled earlier